Piston guide key arrangement for brass instrument



July 17, 1962 B. GREENLEAF 3,044,339

PISTON GUIDE KEY ARRANGEMENT FOR BRASS INSTRUMENT Filed March 14, 1960 si' "I 3,044,339 PIS'I'ON GUIDE KEY ARRANGEMEN'I FR BRASS INSTRUMENT Leland B. Greenleaf, Elkhart, Ind., assigner to C. G. Conn, Ltd., Elkhart, Ind., a corporation of Indiana Filed Mar. 14, 1940, Ser. No. 14,771

' 5 Claims. (Cl. 84-392) This invention relates generally to brass-wind instruments and in particular to the piston construction in the valve assembly of such instruments.

Brass-wind instruments such as cornets, trumpets, and baritones utilize valve assemblies in producing various musical notes and these valve assemblies long have been provided in a variety of constructions. Although basic operating principles of these valve type brass-wind instruments are Well-known, optimum performance and construction-have not been achieved. In such musical instruments the quality of musical notes produced is dependent upon the musician and the structure of the musical instrument, especially the valve assembly. The quality of material used, the dimensional accuracy of the internal parts, and the free, silent movement of the pistons in the valve units are to be given primary consideration. During construction of these musical instruments the close tolerance and the finish on many component parts present problems, especially where mass production techniques are employed and the likelihood of marring is increased.

Thus, it is an object of the present invention to provide an improved valve construction for use in brass-wind musical instruments. .f

Another object of the invention is to provide a valve structure used in brass-wind musical instruments which facilitates rapid construction without sacrificing any of the performance qualities of the instrument.

A feature of the invention is the provision of a piston guide key of sandwich construction adapted for use in brass-wind musical instruments. The sandwich may include a plastic guide member to minimize friction, and

metal plates on each side for protecting such guide member.

Another feature of the invention is the provision of a piston guide having a key engaging a slot in the cylinder and which prevents the piston from turning, thereby improving the entire valve structure. n

rFlG. 1 is a plan View of a typical brass-wind instrument, a cornet which utilizes valve assemblies wherein the invention is incorporated;

FIG. 2 is an enlarged sectional View along line 2-2 of FIG. l, of a valve assembly incorporating the invention; and

FIG. 3 is an enlarged detailed plan view showing the piston guide key along line 3-3 of FIG. 2.

In practicing the invention a piston guide key is provided for coupling to a piston, all of which is inserted in the valve cylinder of a brass-wind musical instrument. The key has a boss engaging the piston to prevent turning with respect to the piston. This key is constructed of a plastic material such as nylon and is sandwiched between relatively thinrnetallic members. The metal plates afford impact protection to the plastic member during assembly of the musical instrument and yalso protect the plastic member while the instrument is being played. The key has a projecting portion which moves in a slot in the cylinder. The boss Aon'the key is located between the valve stern opening therein and the projecting portion of the key assembly, and extends perpendicular to the metallic plates into the upper piston section. The entire key assembly moves axially in the valve cylinder and causes the piston to move in a free and silent manner. The outer edge of the plastic portion of the key extends outwardly from the metallic plates to the cylinder wall of the valve casing thus insuring minimum friction between the key and the cylinder.

Referring now to the drawings, PIG. 1 illustrates a cornet musical instrument 10 having valve assemblies 12 wherein the invention is utilized. Valve assemblies 12 are used in brass wind instruments wherein the passage of air through the instrument is varied according to the position of the valve pistons in a manner well-known in the art.

FIG. 2 shows a cross-sectional view of valve assembly 12 in FIG. l along line 2 2 of FIG. l. The valve assembly includes a valve casing 154 of tubular or cylindrical construction. The lower end 15 of valve casing 14 is closed by a threaded lower cap member 16. The upper end 17 of the valve casing 14 is closed by an upper threaded cap member 18 which has a sleeved opening l20 through which passes valve stem 38.

Within valve casing 14 is a slide assembly 24 which includes tubular piston casing 26 having an aperture 28. The upper end of piston casing 26 is closed by an upper plate member 30 having a central threaded aperture 32, and offset aperture 34 wherein a boss 36 of piston guide key 42 is located. A threaded valve stem 38 is screwed to central aperture 32 of upper plate member 30. Valve stem 3S has a finger pad 40 connected to its upper end for actuation of piston casing 26. Spring 48 maintains piston casing 26 in a iixed position except when it is actuated.

The piston casing position relative to valve casing 14 is maintained by piston guide key 42 consisting of nylon or plastic member `44 sandwiched between metallic plates 246 and 49. During assembly of the instrument, the plates protect the nylon or plastic member `44 from damage and while the instrument is being played the metallic plates 46 and 49 keep the plastic member 44 from being warped or disfigured. It will be understood that the plastic member 44 of the guide key 42 may comprise any suitable resilient material. 'Ihemember 44 has a projection 45 having chamfered edges which extends into the keyway 22 to hold the guide key in a desired rotary position. The boss 36 on the plastic member 44 extends in the offset aperture 34 of upper plate member 30 to hold the piston casing 26 in the desired rotary position with respect to the valve casing 14.

Thus, the piston guide key 42 is constructed of plastic member 44 and metallic plates 46 and 49. Member 44 has an opening 51 in the center thereof and plates `46 and `49 have aligned openings 52 and 53 respectively to receive valve stem 38 therethrough. Plastic member 44 has a boss 43 which tits in opening 47 of upper metallic plate 46, and the boss 36 of the plastic member 44 goes through opening 50 in lower metallic plate 49 and into olfset aperture 34 of upper plate member 30, thereby positioning piston casing 26 in relation to the valve casing 14 as will become more apparent from FIG. 3.

FIG. 3 is a cross-sectional view along line 3-3 of FIG. 2 showing the position of the piston guide key in keyvvay 22. Upper metallic plate 46 covers plastic member 41 except at the point of contact 54 of projectionA 45 with keyway y22 where only the plastic member 44 makes contact with the keyway. The lower metallic plate `49 is similarly constructed so that the contacting end 54 of the projection 45 is exposed and there is no friction between the metallic yplates 46 and 49 and the valve casing 14. The main function of lower metallic plate 49 is to prevent warping of plastic member 44 thereby adding rigidity to the piston guide key structure. Only plastic member 44 of the piston guide lkey is in contact with valve casing 14 yet the proper positioning of piston casing 26 is maintained. Aotuation of finger pad 40 moves valve stem 38 and piston casing 26 thereby changing the registry of aperture 28 to insert or Patented July 17, 1,962`

eliminate lengths of tubing. thereby changing the total horn length to produce various musical notes. Shoulder 39 of valve stern 38 engages plate 46 to move key 42 with the valve stem 38. The piston guide key 42 holds the piston casing 26 in the desired rotary position with respect to valve casing 14 during the sliding movement.

Thus, lthe invention provides for an improved construction of piston guide keys thereby improving the valve assembly construction of brass wind instruments.

I claim:

l. In a brass-wind instrument, a cylindrical valve casing having an internal keyway, a bottom valve cap closing the bottom of said valve casing, a top valve cap having a central opening and closing the top of said valve casing, a slide piston casing positioned inside said valve casing for smooth movement along the inner Wall thereof, said slide piston casing including a top plate closing the top end of said piston casing and having a central opening and an offset opening, a guide -key having a central opening, a boss projecting parallel thereto, and a projection `for engagement in said valve casing keyway, said guide key boss being adapted to be positioned in said top plate offset opening and said central opening thereof being aligned with said central opening of said top plate, a valve stem secured in said central opening in said top plate and extending upwardly through said central opening in said guide key and through said central opening in said top valve cap, said valve stem being operable to move said slide piston casing within said valve casing, and spring means positioned in the lower portion of said valve casing engaging said bottom valve cap and cooperable with said slide piston casing to maintain said slide piston and said valve stem in an upward position, actuation of said valve stem and said slide piston causing axial movement in a predetermined rotary position determined by said piston guide key projection moving along the keyway of said valve casing.

2. In a brass-wind musical instrument, a tubular valve casing having a keyway along the inner wall, a top valve cap having a central opening and closing the top of said valve casing, a slide piston positioned inside said valve casing for movement therein, said slide. valve piston including a top plate closing the ytop end of said piston casing and having a central opening and an oiset opening, a valve stem secured in the central opening in said top plate and extending upwardly through the central opening in said top valve cap, a guide key including a pair of metallic members and a resilient member sandwiched between said metallic members and having an opening, a boss, and a projection for engagement in said valve casing keyway, said guide key boss being adapted to be positioned in said top plate otlset opening, said guide key opening receiving said valve stem therein, said valve stem being operable to move said slide piston withinl said valve casing, and a spring positioned in the lower portion of said valve casing and cooperable with said slide piston to urge the same upwardly, actuation of said valve stem causing said slide piston and said guide key-to move inside said valve casing yand along said valve casing keyway with said guide key maintainingsaid piston in predetermined rotary position in said valve casing.

3. In a brass-wind musical instrument, a tubular valve casing having an internal keyway, a bottom valve cap closing the bottom of said valve casing, a top valve cap having a central opening and closing the top of said Valve casing, a slide piston positioned inside said .having a central opening, said nylon member having a boss, and a projection for engagement in the keyway of Said valve casing, said metallic members having projections which are smaller than the projection on said nylon member, said guide key boss being adapted to be positioned in said `top plate oiiset opening, said guide key central opening and said top plate central opening being aligned, a valve stem secured in said central opening in said top plate and extending upwardly through said central opening in said guide key and through the central opening in said top valve cap, said valve stem being operable to move said slide piston within said valve casing, and spring means positioned in the lower portion of said valve casing engaging said bottom valve cap and cooperable with said slide piston and said guide key to urge the same in an upward position, actuation of said valve stem causing said slide piston and said guide key 'to move within said valve casing, movement therein being determined by engagement of said guide key in the keyway Iof said valve casing, said nylon member of said guide key maintaining sliding contact along said keyway with said metallic members of said guide key being spaced from said keyway.

4. In a brass wind instrument including a valve casing having a keyway formed therein, a piston guide key assembly including a resilient member having an opening adapted to receive a valve stem therethrough, a positioning boss formed on said resilient member, said resilient member having a radially extending projection formed with chamfered edges, upper and lower metallic members on opposite sides of said resilient member each having a plurality of openings therethrough, said metallic member openings arranged in substantial alignment with said resilient member opening and said positioning boss respectively, said metallic members each having a protruding portion smaller than said projection of said resilient member, said projecting portion of said resilient member being positioned in engagement with the keyway of the valve casing for guiding-the key assembly, with said protruding portions of said metallic members being n spaced from the keyway.

5. ln a brass wind musical instrument having a valve with a stem, a piston `guide key including a resilient member having an opening adapted to receive the valve stem therethrough said member having iirst and second opposite Surfaces with guiding means upon each of said surfaces, a iirst metallic member adapted to be mounted upon said first surface and having an opening formed therein to receive said iirst surface guiding means, a second metallic member adapted to be mounted upon said second surface and having an opening vformed therein through which said second surface guiding means extends, said irst and said second metallic members having further openings formed therethrough aligned with said resilient member opening, whereby said guide key assumes a generally sandwich-shaped configuration.

References Cited in the iile of this patent UNITED STATES PATENTS 1,716,917 Carlson lune l1, 1929 1,879,462 Petersen Sept. 27, 1932 2,929,292 Greenleaf et al Mar. 22, 1960 

